For certain applications, the body to be produced should have only minimal deformations after the assembly (the permissible range of deformation lies in the nanometer range). These applications include the production of larger bodies made of several individual bodies. The minimal deformations are preferably at the mirrored surfaces, measurement surfaces or support surfaces for other components. Not only is the size of the body to be produced relevant, but especially its form, such as inner edges. The application of these bodies is preferably in areas wherein nanometers are a relevant size such as in microscopy, astronomy, et cetera.
Essentially two methods are known in the state of the art of fine assembly technology for joining two bodies tightly to each other. These methods are presented as (a) and (b) below.
(a) When bodies are wrung to each other, optical surfaces are joined to each other via the van der Waal forces. Wringing is primarily used for force-tight temporary connections in manufacture. It is a disadvantage in this method that the two bodies joined by wringing easily separate because of liquids which wet the connecting edges. Wringing is also not necessarily resistant to vibration.
In production, wringing is used as a permanent connection for small optical elements having dimensions in the millimeter range. Large elements having dimensions in the centimeter range cannot be joined in this manner with the reliability required for a permanent connection.
Wringing can be improved and be made more reliable by means of a holding lacquer and/or an adhesive material outside of the wringing surfaces in order to increase the durability of the connection. However, the connection cannot be perfected.
(b) When applying adhesive in the absence of tension, the adhesive locations are usually optimized by a clever configuration of the adhesive locations (optimization of the adhesive gap and the adhesive pads). With this optimization, basic requirements (adhesive gaps 1/10 mm, pads 6.times.6 mm) are considered in accordance with the state of the art.
Glued parts have the significant disadvantage that a force-tight and form-tight connection is not necessarily possible. The unavoidable creeping of the connection and the maladjustment of the parts to each other caused thereby likewise generates corresponding problems in some applications.
U.S. Pat. No. 4,826,303 discloses an arrangement for connecting at least two bodies with the bodies being connected to each other via a wedge-shaped connecting member without thermal constraining forces occurring. This arrangement has the disadvantage that both bodies must be reworked after being joined because the wedge-shaped connecting member generates intense forces at the connecting surfaces. On the other hand, this connection is very stable.
German patent publication 3,934,546 shows an arrangement for adhesive-connecting two bodies by means of intermediate pieces. The intermediate pieces are placed up to the surfaces of the two bodies and the surface cannot be used in those regions.